As disclosed in Japanese Patent Kokai Nos. 136,240/87, 152,536/87, 152,537/87, 170,221/94, etc., by the present inventors, methods for dehydrating hydrous matters using saccharides are those which exert dehydrating powers of anhydrous saccharides by allowing them to entrap moisture and to be converted into their hydrous crystalline forms. Unlike heat drying, these methods do not require severe conditions and have features that they convert hydrous matters into dehydrated products without denaturing or deteriorating them.
However, it was revealed that, among the above methods, the one disclosed in Japanese Patent Kokai No. 152,536/87, where anhydrous aldohexoses such as anhydrous glucose and anhydrous galactose are used, has poor preservation stability of dehydrated products because, in spite of their relatively high dehydration powers, the saccharides are highly reactive or easily react with amino acids, peptides, etc., and cause browning reaction. It was also found that such anhydrous aldohexoses are not converted into any hydrous form even under a relatively high humid condition and have only a poor dehydrating power. As for the methods using anhydrous maltose and palatinose, which are respectively disclosed in Japanese Patent Kokai Nos. 136,240/87 and 152,537/87, it was found that there still remains anxiety about stability of dehydrated products when preserved for a relatively long period of time, because of their inherent reducibilities, though they are relatively low. In addition, these methods have the demerit that they require a relatively large amount of anhydrous maltose or palatinose as a dehydrating agent because these saccharides have only a relatively-low-moisture-entrapping power as low as about 5% (w/w) to each of their weights.
Since the non-reducing anhydrous glycosyl fructosides such as anhydrous raffinose, anhydrous erlose, and anhydrous melezitose, which are disclosed in Japanese Patent Kokai No. 152,537/87, have no reducing power, these saccharides would be neither react with amino acids and peptides nor cause browning reaction, and they also have advantageous stability for a relatively long period of time. The above saccharides, however, have an intramolecular fructoside bond poor in acid tolerance, speculating that they should not necessarily be appropriately used as dehydrating agents for acid hydrous matters. Accordingly, there still remains anxiety about the stability of dehydrated products produced thereby. While anhydrous α,α-trehalose, disclosed in Japanese Patent Kokai No. 170,221/94, has no reducing power and satisfactory stabilizes dehydrated products for a relatively long period of time. Due to an activity of entrapping a relatively large amount of moisture as high as about 10% (w/w), α,α-trehalose would be more suitably used than the above-mentioned other saccharide. The method, however, still needs a relatively large amount of anhydrous α,α-trehalose for dehydration, and therefore another dehydrating agent having a higher moisture and/or drying efficiency have been in great demand.